People usually travel via a personal vehicle, public transportation systems such as a bus, a train, or an underground transportation system. People choosing public transportation systems often face a problem of a long-distance walk from a departure location to a public transportation station, and/or from the public transportation station to a destination. Under this situation, some people may choose to ride a bike and carry the bike to the public transportation system.
The conventional personal transportation devices include one or more driving wheels such as a bicycle, a tricycle or a balanced unicycle. However, these personal transportation devices travel on the ground via wheels and cannot meet the needs for different driving environments. Further, they are not convenient to be carried by the users.